DK167025B - IONIC COPOLYMER WITH GOOD LOW TEMPERATURE CHARACTERISTICS, ITS MANUFACTURING AND USE - Google Patents

Description

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DK 167025 B

The present invention relates to ionic copolymers, in particular ionic copolymers having a low degree of chain branching, a process for their preparation and their use.

Copolymers of ethylene and acrylic or methacrylic acids partially neutralized with metal ions such as sodium or zinc ions (ethylene ionomers) are well known and are tough resin resins with a combination of good tensile properties and excellent abrasion resistance.

Their disadvantage is that at low temperatures, they become overly stiff.

U.S. Patent No. 3,264,272 describes the ethylene / methacrylic acid / acrylic acid ester copolymers and ionomers prepared from these materials. Polymerization is described at high pressures of 50-3,000 atm. and elevated temperatures of 150-300 ° C in the presence of a free radical polymerization initiator.

In DE Publication No. 2,341,462, ethylene / acrylate / acid copolymers and ionomers and reactor temperatures of 150-300 ° C are described. However, the examples in the specification 20 are carried out only at polymerization temperatures of 215 ° C or more.

The document mentions a large number of acrylates, e.g. isobutyl acrylate, as well as methacrylates, maleate and fumarates. Furthermore, it is mentioned that the prepared ionomers exhibit flexibility and high oxygen permeability, but not low temperature flexibility.

According to the present invention there is provided an ionic copolymer of ethylene, unsaturated carboxylic acid and at least one softening comonomer, which ionic copolymer has good low temperature properties and is characterized in that the unsaturated carboxylic acid is selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, fumaric acid, and semesters of maleic acid, fumaric acid and itaconic acid and the softening comonomer is selected from n-propyl acrylate, n-butyl acrylate,

DK 167025 B

2 2 -ethylhexylacrylic at and 2-methoxyethyl acrylic at which copolymer contains from 10 to 87% by weight of ethylene, from 3 to 30% by weight of unsaturated acid and from 10 to 60% by weight of softening comonomer, the copolymer has from 3 to 90% of the carboxylic acid groups ionized by neutralization with metal ion selected from sodium, potassium, zinc, calcium, magnesium, lithium, aluminum, nickel and chromium, and the copolymer is characterized by a low degree of chain branching of up to 2.8 chain branches per. 1000 skeletal methylene units.

Further, according to the invention, there is provided a process for preparing an ionic copolymer of good low temperature properties according to the invention, the method being selected from direct copolymerization and graft copolymerization, wherein (A) the direct copolymerization comprises polymerization of ethylene, unsaturated carboxylic acid and at least one comonomers in the presence of free radical polymerization initiator at elevated temperature followed by neutralization of the carboxylic acid groups in the resulting direct copolymer with 20 metal ions, and (B) the graft copolymerization comprises polymerization of ethylene and at least one comonomer in the presence of free radical polymerization initiator by elevated temperature and grafting of unsaturated carboxylic acid or anhydride on the ethylene / -25 comonomer polymer backbone followed by neutralization of the carboxylic acid groups in the resulting graft copolymer with metal ions, and the process is characterized by the fact that as a softening comon n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and 2-methoxyethyl acrylate are used, as the unsaturated acid, an acid selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and semesters of maleic acid, fumaric acid and itaconic acid, which contains from 10 to 87% by weight ethylene, from 3 to 30% by weight 35 acid and from 10 to 60% by weight softening comonomer,

DK 167025 B

3, a polymerization temperature of 100 to 200 ° C is used, whereby 3 to 90% of the carboxyl groups in the copolymer are neutralized with metal ions selected from sodium, potassium, zinc, calcium, magnesium, lithium, aluminum, nickel and 5 chromium.

Surprisingly, these ionomers derived from ethylene, a softening comonomer and methacrylic acid have been found to have good low temperature properties. These copolymers prepared at low reactor temperatures, having a reduced chain 10 degree branching and containing an appropriate softening comonomer, provide ionomers that do not become as rigid at low temperatures and have a significantly improved bending crack resistance (Ross Flex value) compared to ionomers prepared at higher reactor temperatures and containing 15 softening comonomers which do not yield low glass transition temperature homopolymers.

Contrary to the technique known from the aforementioned DE Publication No. 2,341,462, the invention makes a careful selection of normal acrylates 20 (i.e., isoacrylates, methacrylates, fumarates or maleate) and a selection of a suitable temperature range of 100-200 polymerization. ° C (but not higher), preferably below 160 ° C. The core point of the invention is that in order to achieve low temperature flexibility and toughness, a selection in two respects must be made, both a choice of n-acrylates and a choice of low polymerization temperatures. One of these choices is not enough. For example, isobutyl acrylate will not be suitable and a polymerization temperature of 215 ° C will also not be suitable, even using 30 n-butyl acrylate.

Accordingly, the ionomers are useful for injection molded articles, such as ski boots and skate boots, and as coatings for fabrics.

In addition, since the ionic copolymers of the invention have superior low temperature properties and lower hardness than commercially available ionomers, they can act as

DK 167025 B

4 substitute for balata (balata is trans-1,4-polyisoprene) in golf ball jackets. Accordingly, golf balls comprising a core and a sheath, wherein the sheath comprises the ionic copolymer of the invention, will have a similar "melt" and a similar feel to a golf ball made with a balata sheath. The iononomers of the present invention can also be used as modifiers for other thermoplastic materials where they function very effectively as toughening agents.

The invention also relates to the use of an ionic copolymer of the invention in a thermoplastic mixture with material selected from nylon, polypropylene, propylene-ethylene copolymer, linear polyethylene and ethylene / unsaturated carboxylic acid copolymer.

The invention further relates to the use of an ionic copolymer according to the invention as a sheath on a golf ball comprising a core and a sheath.

The polymer of the invention is a copolymer of ethylene, unsaturated carboxylic acid and at least one plasticized copolymer, which is copolymerizable with ethylene and yields a low glass transition temperature homopolymer wherein the copolymer is partially neutralized with a metal ion.

The unsaturated acid is preferably methacrylic acid and acrylic acid.

The softening comonomer is preferably n-butyl acrylate.

The copolymer preferably contains from 60 to 75% by weight of ethylene, from 5 to 15% by weight of unsaturated carboxylic acid, and from 10 to 30% by weight, especially 15 to 25% by weight, softening 30 comonomers.

Preferably, the copolymer of the present invention has ionized from 35 to 75% of the carboxylic acid groups by neutralization with metal ion selected from sodium, potassium, zinc, calcium and magnesium.

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5

The ionic copolymers of the invention can be prepared by direct copolymerization or by graft copolymerization. The direct polymerization process comprises polymerization of ethylene, unsaturated carboxylic acid and softening co-monomer in the presence of a free radical polymerization initiator at elevated temperatures of from 100 to 200 ° C, preferably from 130 to 145 ° C at pressures from 140 to .350 mPa, followed by neutralization of the carboxylic acid groups in the produced direct copolymer with metal ions. A suitable polymerization process is described in detail in U.S. Patent No. 3,264,272 (other than the unexpected benefits obtained by using the lowest possible reactor temperatures).

The seed copolymerization process can be carried out by polymerizing ethylene and plasticizer copolymer in the presence of free radical polymerization initiator at elevated temperatures of from 100 to 200 ° C, preferably from 140 to 160 ° C, at pressures from 140 mPa to 350 mPa, and graft unsaturated. carboxylic acid or anhydride on ethylene / plasticizer comonomer - the polymer backbone and then neutralize the carboxylic acid groups in the resulting graft copolymer with metal ions.

The ionomers of the present invention can be mixed with material selected from nylon, polypropylene, propylene-ethylene copolymers, linear polyethylene and ethylene / unsaturated carboxylic acid copolymers. These mixtures will generally find use as cool thermoplastics.

The iononomers of the invention, which contain the above-mentioned monomers and are prepared at the low reaction temperatures mentioned above, are characterized by a low degree of chain branching, namely up to about 30%. 2.8 chain branches per 1000 skeletal methylene units as determined by C-13 NMR.

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6

The invention is illustrated by the following examples. All parts, percentages and ratios are by weight, unless otherwise stated.

Comparative Example 1 and Example 1

The polymer of Comparative Example 1 containing n-butyl acrylate, ethylene and methacrylic acid is prepared by free radical polymerization at a reactor temperature of 220 ° C and 190 mPa. The monomer addition is adjusted so as to obtain a polymer containing 10.1% methacrylic acid (MAA), 17% n-butyl acrylate (nBA) and 72.9% ethylene.

The polymer (base resin) is converted to a sodium ionomer by reaction with a concentrate containing sodium carbonate. Thus, 1000 g of the copolymer is reacted with 72 g of a concentrate (containing 50% 2002 2002, 0 0 in an ethylene / methacrylic acid copolymer containing 11% MAA and the food melt flow of 100 g / 10 min). The reaction is carried out in a twin screw extruder using the following conditions:

EXTRUDERINGSBETINGELSER

Wormhole Temperature, ° C, Zone Amount Vacuum Water Supply Flow o / m__1_ 2 3 4 5 kg / hr mm Hg cm ^ / hr 50 135 236 247 262 280 2.27 762 20

The polymer of Example 1 is synthesized at 140 ° C and 190 mPa. The comonomer composition is adjusted so as to obtain a composition similar to the composition of the polymer of Comparative Example 1.

The polymer is converted to ionomer using an extrusion procedure similar to that used in Comparative Example 1. In this case, however, 2.27 kg of polymer is mixed with 147 g of a zinc oxide.

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7 oxide concentrate (30% ZnO, 1.5% zinc acetate in E / 10 MAA copolymer). Comparison of the results for the polymers of Comparative Example 1 and Example 1 shows that the polymer prepared at 220 ° C has a higher bending modulus 5 increase at lower temperatures and a much poorer bending crack resistance (Ross Flex value) at -20 ° C. Compositions and properties are summarized in Table I.

C-13 NMR analysis is also performed on the ethyl / n-butyl acrylate / methacrylic acid copolymers of Comparative Example 1 and Example 1 prior to their conversion to ionomers. The results obtained show that the use of low reactor temperatures (140 ° C) has almost halved the number of alkyl branches per liter. 1000 skeletal methylene-15 units compared to a copolymer prepared at a high reactor temperature of 220 ° C (see the chain branch table below).

TABLE-KÆDEFORGRENINGS

2 °

Number of butyl or larger alkyl branch MAA nBA Reactor temp. per minute. 1000 skeleton Example%% ° C-methylene units. C-l 10.1 17.0 220 4.6 25 1 8.5 17.0 140 2.5 30 35

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Examples 2 and 3.

The polymer of Example 2 is prepared at 190 mPa and 195 ° C and with the composition 8.6% MAA, 24% nBA and 67.4% ethylene. This polymer is then converted to a zinc ionomer by reaction with zinc acetate on a two-roll mill. Thus, 100 g of polymer is reacted with 6.6 g of Zn (OAc) 2 / 2H 2 O in 25 cm 2 of water at 200 ° C. The finished ionomer has an MI value of 2.8.

The polymer of Example 3 is prepared in a similar manner to that of Comparative Examples 1 and Examples 1 and 2. However, the reaction is carried out at 140 ° C and an attempt is made to obtain a composition as in Example 2. Thus, a polymer containing 9.4% MAA is prepared. 22.4% nBA and 68.2% ethylene and converted to ionomer.

The conversion to ionomer is achieved by reacting 3 1 kg of polymer with 60 g of Zn (OAc) ^ 21 ° D dissolved in 150 cm of water on a 15 cm bipolar mill at 190-200 ° C. The resulting ionomer is formed and the physical properties investigated.

The results of the study of the ionomer of Example 3 show that it has a lower bending modulus than the ionomer of Example 2 and has a significantly better Ross Flex durability at -20 ° C. Compositions and properties are summarized in Table I.

Comparative Examples 2 and 3.

These polymers are prepared at 140 ° C and 190 mPa and contain 70.3% ethylene, 19.8% isobutyl acrylate (iBA) and 9.9% methacrylic acid and are converted to ionomers. Bending modulus and Ross Flex value for these ionomers show that n-30-butyl acrylate polymers are superior to isobutyl yl acrylate polymers. Homopolymers of iBA have a relatively high glass transition temperature. Compositions and properties are summarized in Table I.

Comparative Examples 2-3 also show that there is little or no difference between sodium and zinc ionizers. The improved bending crack resistance and the o 10

DK 167025 B

Thus, reduced low-temperature stiffness is not to be attributed to the ion type, but the softening comonomer and the degree of chain branching.

Example 4

A mixture of polyamide-66 ("ZytellOl", E.I. du Pont de Nemours and Company) is prepared containing 30% of a zinc ionomer prepared by neutralizing a copolymer of the following composition: E / 28.0 nBA / 10.1 MAA. The melt mixture is produced on a double screw extruder, using a high shear screw mold and a melting temperature of 270 ° C. The resulting polymer blend is injection molded for tensile and bending modulus test rods using standard polyamide-15 molding conditions. The results of the physical properties study of these shaped specimens are summarized below:

Breakage tensile strength ^ 47 mPa

Extension ^ 110% 20 Bending modulus in dry to 1500 mPa state as shaped (2)

Izod jaw impact strength at 23 ° C 14 00 J / m.

at -20 ° C 460 J / m.

25 Footnotes: (1) Tensile strength and percent elongation are determined according to ASTM-638.

(2) Izod notch impact strength is determined according to ASTM-256.

Compared to unmodified polyamide-66 ("Zytel 101"), the results demonstrate the ability of these ionomers to substantially make polyamide tough and provide improved toughness at low temperatures.

35

Claims (15)

An ionic copolymer of ethylene, unsaturated carboxylic acid and at least one softening comonomer, which ionic copolymer has good low temperature properties, characterized in that the unsaturated carboxylic acid is selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and half esters of maleic acid and half esters of maleic acid and that the softening comonomer is selected from n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and 2-methoxyethyl acrylate, which copolymer contains from 10 to 87 wt% ethylene, from 3 to 30 wt% unsaturated acid and from 10 to 60% by weight softening comonomer, the copolymer has ionized from 3 to 90% of the carboxylic acid groups by neutralization with metal ion selected from sodium, potassium, zinc, calcium, magnesium, lithium, aluminum, nickel and chromium, and the copolymer is characterized by a low degree of chain branch of up to 2.8 chain branches per 1000 skeletal methylene units. Ionic copolymer according to claim 1, characterized in that the softening comonomer is n-butyl acrylate. 3. Ionic copolymer according to claim 1, characterized in that it is a direct copolymer and that the unsaturated acid is selected from acrylic acid and methacrylic acid. Ionic copolymer according to claim 3, characterized in that ethylene is present in an amount of from 60 to 75% by weight, the unsaturated acid is present in an amount of from 5 to 15% by weight, and the softening agent. comonomers are present in an amount of from 15 to 25% by weight. Ionic copolymer according to claim 4, characterized in that it has from 35 to 75% of carboxylic acid groups ionized by neutralization with metal ion selected from sodium, potassium, zinc, calcium and magnesium. Ionic copolymer according to claim 1, characterized in that it is a graft copolymer. A process for preparing an ionic copolymer with good low temperature properties according to claim 1, wherein the DK 167025 B process is selected from direct copolymerization and graft copolymerization, wherein (A) the direct copolymerization comprises polymerization of ethylene, unsaturated carboxylic acid and at least one comonomer. 5. presence of free-radical polymerization initiator at elevated temperature followed by neutralization of the carboxylic acid groups in the resulting direct copolymer with metal ions, and (B) the graft copolymerization comprises polymerization of 10 ethylene and at least one comonomer in the presence of free-radical-polymerization initiator at elevated temperature and grafting of unsaturated carboxylic acid or anhydride on the ethylene / comonomer polymer backbone, followed by neutralization of the carboxylic acid groups in the resulting graft copolymer with metal ions, characterized in that n-propyl acrylate, n-butyl acrylate, 2-ethylacrylate, rylate and 2-methoxyethyl acrylate, that as the unsaturated acid is used an acid selected from acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and semesters of maleic acid, fumaric acid and itaconic acid containing copolymer from 10 to 87% by weight of ethylene, from 3 to 30% by weight acid and from 10 to 60% by weight softening comonomer using a polymerization temperature of 100 to 200 ° C, whereby 25 to 90% of the carboxyl groups in the copolymer are neutralized with metal ions selected from sodium, potassium , zinc, calcium, magnesium, lithium, aluminum, nickel and chromium. Process according to claim 7, characterized in that n-30-butyl acrylate is used as a softening comonomer. Process according to claim 7, characterized in that it is carried out by direct copolymerization and the unsaturated acid is selected from acrylic acid and methacrylic acid. Process according to claims 7-9, characterized in that the polymerization temperature is from 130 to DK 167025 B 145 ° C and that the polymerization pressure is from 140 to 350 mPa. Process according to claim 10, characterized in that the ethylene is present in an amount of from 65 to 80% by weight, the unsaturated acid is present in an amount of 5 from 5 to 15% by weight, and the softening comonomer is present in an amount of from 10 to 25% by weight. Process according to claim 9, characterized in that the copolymer has neutralized from 35 to 75% of the carboxylic acid groups with metal ion selected from sodium, potassium, zinc, calcium and magnesium. Process according to claim 7, characterized in that it is carried out by graft copolymerization. Use of an ionic copolymer according to claim 1, 4 or 6 in a thermoplastic mixture with material selected from nylon, polypropylene, propylene-ethylene copolymer, linear polyethylene and ethylene / unsaturated carboxylic acid copolymer. Use of an ionic copolymer according to claims 1, 3, 5 or 6 as a sheath on a golf ball comprising a core 20 and a sheath.